Originally Posted by
Someone Somewhere
Probably so-called 'bistable' relays. I think they use springs and an over-centre mechanism to latch in position, similar to a toggle switch. Just the actuation is by two coils (or one coil operated in two polarities), rather than by fingers.
Interesting. Thanks. I guess I would have to find a part number and datasheet to really know. Possibly Leach.
https://www.leachint.com/wp-content/...tique_M402.pdf
Not sure I understand the symbology in that document, either.
I see the fuel spar valve has 3 levels of "latching". One of the latching fuel relays shown above controls a spar valve latching relay. The spar valve latching relay controls the polarity of the spar valve DC motor. If power is lost from the spar valve latching relay, the motor is obviously not going to move, keeping the valve in its last commanded position.